Auroral Chorus V: Sferics Anthology
- ELF-VLF "Natural Radio" - : Our planet Earth is alive with a vast amount of natural-electricity - Lightning!
Every lightning bolt within 3,000 miles or about 5,000 km of the VLF receiver creates a pop or a crackle in a VLF receiver's audio output, especially at these AUDIO-frequency radio-waves.
Because lightning storms produce vast amounts of radio energy at VLF frequencies, the World-Wide Lightning Location Network (wwlln.net) employs VLF receivers to direction-find and map lightning strokes via the very VLF signals presented herein.
The majority of natural VLF radio audio files on this page are in STEREO employing my WR-9STL dual-loop receiver. In the stereo (dual-loop/orthogonally-oriented) natural VLF radio recordings on this page, you can hear the directionality of the two VLF-loop antennas and the stereo-effects because of the differing directions that all of the lightning "sferics" are originating from - whether cloud-to-cloud lightning (sometimes creating multi-burst lightning strings), to clear pops of ground strikes. Maybe many of the lightning bolts making a sferic also launch Sprites toward the ionosphere!
I am fascinated by lightning and associated electromagnetic-emissions of lightning (and they spawn whistlers occasionally, too) as much as the other sounds of Earth's natural-VLF-radio phenomena such as whistlers and dawn-chorus.
Lightning static - also called "atmospherics" or "sferics" - can be interesting to listen to, and I am undertaking the project of stereophonic recording of lightning sferics with a dual, cross-azimuth loop-antenna receiving system.
The sounds of sferics in stereo are quite beautiful! A particularly beautiful stereo tweek/whistler recording is the 33 minute track/23 August 2012/0745UT file (recorded in Inyo County, California) to the right or downloadable links below.
What causes the "ringyness" or "pingyness" of lightning atmospherics/sferics (at nighttime) is caused by the lowest layers of the ionosphere and Earth's surface and also Ocean surfaces forming a kind-of "waveguide" that enhances the approximately 1.7 kHz (+/- 200 Hz) audio-frequencies of these electromagnetic signals. They are called "Tweeks." (They are not EQ signals as some have assumed).
Tweeks can always sound pretty and enjoyable when other VLF emissions from up farther within the Magnetosphere fail to occur. Like raindrops on a rooftop, the sounds of Tweeks can be soothing to some.
Whistlers are precipitated by lightning strokes as you will hear in all of these amazing and beautiful recordings. Enjoy!
In March 2015 I uploaded several tracks that contain compilation-edits of various natural VLF radio field-recording expeditions to locations in Canada and Alaska within the auroral-zone (where aurora are most frequently visible). Auroral-zone locations of Earth can be considered "VLF hot-spots."
Stephen P. McGreevy - N6NKS - Updated 06 November 2017
ADDITIONS: A few chosen compilations of other field-recordings of awesome VLF sounds from much higher geo-magnetic latitude locations (northern Alberta, Canada June 1996) have been added to this album here at Internet Archives. In you listen to the Alberta June 1996 recordings, you will likely notice that many of the quite bizzarre natural radio sounds are initiated by the pop and crash of lightning strokes. SpM
All of my mono and stereo VLF recordings herein are fully public-domain recordings - Enjoy!
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